Control point policy optimization using genetic algorithms

This paper describes the application of an integrated Genetic Algorithm (GA)/Discrete Event Simulation model for selecting optimum values for Critical Point Policy (CPP) hedging time and buffer size parameters. The CPP is shown to perform well, when compared with the Critical Ratio priority rule, in terms of improving service levels, particularly when subject to conditions where buffer sizes and Takt times are required to be small. The technique developed involves buffer sizes being chosen by a GA according to a constraint on the total storage space available within the system. A method is described for reducing the number of variables that the GA needs to deal with, hence, improving the efficiency of the GA optimization process. The development and application work reported also provides further understanding into how and when the CPP should be applied.     

Process cost modelling using neural networks

One method of establishing cost-estimating relationships (CERs) that appears to offer advantages is that of neural networks as they are 'model-free estimators', hence providing key advantages over traditional techniques, e.g. regression analysis. However, the complexity of neural network (NN) structures and the availability of a wide range of structural alternatives may make it difficult to select an appropriate network for a specific cost-modelling requirement. The current work is aimed at resolving this issue by examining the use of the Taguchi methodology for identifying NN structural elements. The Taguchi methodology has been used to identify 'best' and 'poorest' NN structures and the models developed using these structures compared with regression-based models in terms of their estimating accuracy. The robustness of these models is then examined in terms of the effects on their estimating accuracy of varying the number of data points used in their development and varying the number of predictor variables within the models.     

Seed-oil-based coolants for transformers

Fire safety, firewalls, deluge systems, and fluid containment are some of the fire protection problems users face when installing mineral oil filled transformers. Aging substation infrastructure, environmental protection, and resource sustainability are other growing issues. To address these concerns, natural ester fluids are being utilized for their superior fire, environmental, and life-extension properties. Natural ester fluid offers the highest fire point of any insulating fluid at 360 °C and a flawless fire safety record through ten years and more than 45,000 installations. Natural ester fluid is manufactured from seed oil and biodegradable additives, making it readily biodegradable in the case of a spill. The combination of fire safety and biodegradability typically eliminates the traditional need for firewalls and deluge systems and can reduce spill containment, reporting, and remediation requirements. Properties unique to certain seed oils help to slow down the insulation aging rate and to stabilize the electrical performance of the transformer [1].     

An Investigation of Group Leaders' Intentions.

Stimulated recall methods were used to assist 34 group leaders in recalling their intentions (i.e., purposes, plans, goals) in relation to interventions they made in a group session. A total of 835 intentions were reported by the leaders and were categorized into 6 separate intention categories by trained judges. The categories included directing the group, gathering information and assessing members, challenging members, attending to and validating members' experiences, directing self, and promoting connections and interactions among group members. Multidimensional scaling procedures revealed 4 intention clusters: Promoting Insight/Change, Planning and Guiding, Attending, and Assessing Growth. Limitations of the study are addressed, along with implications for future research and group leader training. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Feedback exchange in counseling groups: An analysis of message content and receiver acceptance as a function of leader versus member delivery, session, and valence.

36 university students and 27 community residents (all Ss aged 20–47 yrs) participated in 9 6-wk personal-growth groups led by 18 advanced doctoral students. 410 items of interpersonal feedback (both leader-to-member and member-to-member) were analyzed for message content quality and recipient acceptance. Findings indicate that leader feedback was generally of higher quality than member feedback but not more readily accepted. There was a significant tendency for feedback to be of higher quality and more accepted in later than in earlier sessions, but this tendency was not consistent across other conditions. The strongest effects were for valence, with positive feedback consistently more accepted than negative. Positive feedback consistently received higher ratings of message content quality than did negative feedback. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The GaAs P-N-P-N laser diode

The general structure of double-heterojunction diode lasers is shown to be consistent with the required geometry of the Shockley diode or p-n-p-n switch. When the two devices are combined in a single structure, there results an extremely simple source of high optical power (>0.5-W) pulses of very short duration (<10 ns) without the need for a complex external driver. In principle, pulse triggering and repetition rate are easily controlled, suggesting that the device has potential application in pulse-coded optical communication systems.     

Portable electronic storage systems

Notebook, palmtop, and pen-based computers have unique storage requirements. In addition to a rapid growth in capacity to support emerging multimedia applications, portable systems require small, removable media; high shock resistance; thermal resilience; and light-weight, unique form factors dictated by ergonomic constraints and choices. It is argued that storage is the critical enabling technology for many new multimedia applications and addressing its rapidly increasing requirements is key to bringing forward this new technology     

Computer controlled brilliant cutting of flat glass

Brilliant cutting is a grinding process used to cut and polish decorative patterns into flat glass. It is a labour intensive process and essentially requires a skilled cutter to present a sheet of flat glass to a grinding wheel. Manual manipulation of the glass is then used to enable the grinding wheel to cut the desired pattern into the glass. This paper describes a CAD/CAM system which has been developed to replace this manual process. The basic design concept involved allowing a grinding wheel to move whilst keeping the workpiece stationary. Fiveaxis manipulation of the grinding wheel was required to ensure that a wide range of decorative shapes could be successfully generated and CNC part programs were developed from 2D drawing data.